List of most massive stars

This is a list of the most-massive stars so far discovered. The list is ordered by solar mass (1 solar mass = the mass of Earth's Sun).

Stellar mass is the most important attribute of a star. Combined with chemical compositions, mass determines a star’s luminosity, its physical size, and its ultimate fate. Due to their mass, most of the stars below will eventually go supernova or hypernova, and form black holes.

Uncertainties and caveats

Most of the masses listed below are contested, and being the subject of current research, are constantly being revised.

The masses listed in the table below are inferred from theory, using difficult measurements of the stars’ temperatures and absolute brightnesses. All the listed masses are uncertain: both the theory and the measurements are pushing the limits of current knowledge and technology. Either measurement or theory, or both, could be incorrect. An example is VV Cephei, which, depending on which property of the star is examined, could be between 25 to 40, or 100 solar masses.

Massive stars are rare; astronomers must look very far from the Earth to find one. All the listed stars are many thousands of light years away, and that alone makes measurements difficult. In addition to being far away, it seems that most stars of such extreme mass are surrounded by clouds of outflowing gas; the surrounding gas obscures the already difficult-to-obtain measurements of the stars’ temperatures and brightnesses, and greatly complicates the issue of measuring their internal chemical compositions. For some methods, different chemical composition leads to different mass estimates.

In addition, the clouds of gas obscure observations of whether the star is just one supermassive star, or instead a multiple star system. A number of the stars below may actually consist of two or more companions in close orbit, each star being massive in itself, but not necessary supermassive. Alternatively, it is possible for a multiple-star system to still have one (or more) supermassive star, with one (or more) much smaller companion(s). Without being able to see inside of the surrounding cloud, it is difficult to know which scenario might be the case.

Amongst the most reliable listed masses are NGC 3603-A1 and WR20a+b, which were obtained from orbital measurements. They are both members of (different) binary star systems, and it is possible to measure in both cases the individual masses of the two stars by studying their orbital motion, via Kepler's laws of planetary motion. This involves measuring their radial velocities and also their light curves, as both stars are eclipsing binaries.

Stellar evolution

A number of the stars may have started out with even greater masses than those currently estimated, but due to the huge amount of gas they outflow, and sub-supernova and supernova impostor explosion events, have lost many tens of solar masses of material.

Also there are a number of supernovae and hypernovae remnants whose precursor stars' masses can be estimated based on pre-super/hypernova observations, the energy of the super/hypernova, and the type of super/hypernova event. These stars (if they had not exploded) would have easily made appearances in this list (however they are not shown below).

List of the most massive stars

Known stars with an estimated mass of 25 or greater solar masses. Masses are their current assumed mass, not their initial (formation) mass:

Star name	Solar mass
R136a1 [1]	265–320
WR 101e	150–160
HD 269810	150
Peony Nebula Star	150
LBV 1806-20	130–200
HD 93129 A + B[2][3]	A=120–127, B=80
HD 93250	118
NGC 3603-A1	A=116, B=89
Pismis 24-1 A + B[4][5]	A=100–120, B=100
Arches cluster[6][7][8]	Many stars, 100–130
Pismis 24-17[5]	100
Hineliun	100
S Doradus	100
Eta Carinae[9]	90–100
Cygnus OB2-12	92
WR20 a + b[10]	A=83, B=82
The Pistol Star	80–150
Melnick 42[11][12][13]	80–100
HD 97950[14][15]	80
Sk-71 51[16]	80
R 126	70
Companion to M33 X-7[17]	70
LY Aurigae	64
LH54-425 A + B[18]	A=62, B=37
Var 83 in M33[19]	60–85
Sher 25 in NGC 3603[20]	60
Zeta-1 Scorpii[21]	60
Zeta Puppis[22]	59
WR22[23]	55–74
Plaskett A + B[24][25]	A=43, B=51
AG Carinae	50
WR102c[26]	45–55
IRS-8*[27]	44.5
HD 5980 A + B[28][29][30]	A=40–62, B=30
DL Crucis	40–50
Epsilon Orionis	40
HD 148937[31][32]	40
IRAS 05423-7120[16]	40
Rho Cassiopeiae	40
RW Cephei	40
Theta1 Orionis C	40
Xi Persei[33]	40
V382 Carinae	39
Companion to NGC300 X-1[34]	38
Cluster R136a	12 stars, all 37–76
Chi2 Orionis[35]	35–40
Companion to IC10 X-1[36]	35
Nu Aquilae	30-45
VY Canis Majoris[37][38]	30–40
19 Cephei	30–35
Gamma Velorum A	30
P Cygni	30
R 66	30
Eta Canis Majoris	30
Zeta Orionis	28
IRS 15[39]	26
VV Cephei	25–40
Alpha Camelopardalis[40][41]	25–30
6 Cassiopeiae[42][43]	25
EZ Canis Majoris	25
KY Cygni[44]	25
Mu Cephei	25
V509 Cassiopeiae	25
NGC 7538 S[45]	20–40
S Monocerotis A[46]	18–30
WR47	8–48

Black holes

Main articles: Black hole and List of black holes

Black holes are the end point evolution of massive stars. Technically they are not stars, as they no longer generate heat and light via nuclear fusion in their cores.

• Micro black holes are hypothetical black holes. They can be created by particle accelerators.^{[citation needed]}
• Stellar black holes are objects with approx. 4-15 times the mass of our Sun.
• Intermediate-mass black holes range from 100-10000 times the mass of our Sun.
• Supermassive black holes are in the range of millions or billions of solar masses.

Eddington's size limit

Main article: Eddington luminosity

Astronomers have long theorized that as a protostar grows to a size beyond 120 solar masses, something drastic must happen. Although the limit can be stretched for very early Population III stars, if any stars existed above 120 solar mass, they would challenge current theories of stellar evolution.^{[citation needed]}

The limit on mass arises because stars of greater mass have a higher rate of core energy generation, which is higher far out of proportion to their greater mass. For a sufficiently massive star, the outward pressure of radiant energy generated by nuclear fusion in the star’s core exceeds the inward pull of its own gravity. This is called the Eddington limit. Beyond this limit, a star ought to push itself apart, or at least shed enough mass to reduce its internal energy generation to a lower, maintainable rate. In theory, a more massive star could not hold itself together, because of the mass loss resulting from the outflow of stellar material.

Studying the Arches cluster, which is the densest known cluster of stars in our galaxy, astronomers have confirmed that stars in that cluster do not occur any larger than about 150 solar masses.

See also

Star portal

• Luminous blue variable
• Wolf-Rayet star
• Hypergiant
• List of least massive stars
• List of largest known stars
• List of most luminous stars
• List of brightest stars
• Lists of stars
• Supergiant

References

1. ^ Paul A. Crowther et al (2010) "The R136 star cluster hosts several stars whose individual masses greatly exceed the accepted 150 Msun stellar mass limit", accepted for publication in Monthly Notices of the Royal Astronomical Society. Available at arXiv:1007.3284v1 [1]. Advertised in ESO Press Release 1030 [2]
2. ^ HD 93129A
3. ^ Big and Giant Stars: HD 93129
4. ^ HDE 319718 (Pis 24-1) and the Pismis 24 Cluster
5. ^ ^{a b} http://spacespin.org/article.php/hubble-massive-star-system-pismis-24-1
6. ^ Massive Stars in the Arches Cluster
7. ^ Hubble Weighs In On The Heaviest Stars In The Galaxy
8. ^ [0711.0657] The most massive stars in the Arches cluster
9. ^ http://www.science20.com/news_releases/eta_carinaes_1843_explosion_was_a_mini_supernova_says_researcher
10. ^ http://www.eso.org/public/outreach/press-rel/pr-2008/pr-37-08.html
11. ^ http://www.nasa.gov/home/hqnews/1991/91-008.txt
12. ^ Energy Citations Database (ECD) - - Document #5225537
13. ^ Big and Giant Stars: Melnick 42
14. ^ Big and Giant Stars: HD 97950
15. ^ Quantitative spectroscopy of Wolf-Rayet stars in HD97950 and R136a - the cores o
16. ^ ^{a b} The Blob, the Very Rare Massive Star and the Two Populations - Striking Image of Nebula N214C taken with ESO's NTT at La Silla | SpaceRef - Your Space Reference
17. ^ NASA - Heaviest Stellar Black Hole Discovered in Nearby Galaxy
18. ^ Big and Giant Stars: LH54-425
19. ^ Big and Giant Stars: Var 83
20. ^ Big and Giant Stars: Sher 25
21. ^ http://www.astro.uiuc.edu/~kaler/sow/zeta1sco.html
22. ^ http://www.astro.uiuc.edu/~kaler/sow/naos.html
23. ^ http://adsabs.harvard.edu/full/1995LIACo..32..463R
24. ^ Big and Giant Stars: Plaskett's Star
25. ^ Plaskett's Star
26. ^ http://www.astro.physik.uni-potsdam.de/abstracts/spitzer-andreas.html
27. ^ Does IRS-8 contain the youngest and most massive star in the Galactic Center? | Gemini Observatory
28. ^ Big and Giant Stars: HD 5980
29. ^ ESA - Space Science - First X-ray detection of a colliding-wind binary beyond the Milky Way
30. ^ http://www.esa.int/esaCP/SEMPYIO2UXE_index_0.html
31. ^ http://www.gemini.edu/node/188
32. ^ http://jumk.de/astronomie/big-stars/hd-148937.shtml
33. ^ http://www.astro.uiuc.edu/~kaler/sow/menkib.html
34. ^ http://arxiv.org/abs/0705.1544
35. ^ http://www.astro.uiuc.edu/~kaler/sow/chi2ori.html
36. ^ http://hera.ph1.uni-koeln.de/~heintzma/Spectra/WR_1.htm
37. ^ http://www.daviddarling.info/encyclopedia/V/VY_Canis_Majoris.html
38. ^ http://jumk.de/astronomie/big-stars/vy-canis-majoris.shtml
39. ^ A Remnant Disk around a Young Massive Star
40. ^ http://apod.nasa.gov/apod/ap061124.html
41. ^ http://www.astro.uiuc.edu/~kaler/sow/alphacam.html
42. ^ http://www.astro.uiuc.edu/~kaler/sow/6cas.html
43. ^ http://jumk.de/astronomie/big-stars/6-cassiopeiae.shtml
44. ^ http://jumk.de/astronomie/big-stars/ky-cygni.shtml
45. ^ Witnessing the birth of a massive star
46. ^ http://www.astro.uiuc.edu/~kaler/sow/15mon.html

External links

• Most Massive Star Discovered
• Arches cluster
• How Heavy Can a Star Get?
• LBV 1806-20